Process and plant for manufacturing double-pouch containers

ABSTRACT

In the process and plant for forming double-pouch containers, two continuous external ribbons ( 3 ), facing one another, are fed in an advancement direction to an infeeding zone where a third, central ribbon ( 5 ) is inserted between the external ribbons ( 3 ). The pouches are formed by injecting a forming fluid between the external ribbons ( 3 ) in order to determine an expansion thereof against compartments of two half-molds having a shape which corresponds to a final pouch shape. Each container has two similar pouches, one facing another, which are defined by a pair of external walls and by a central wall coupled along a perimeter thereof to the external walls. The process enables rapid and economical formation of double-pouch containers.

REFERENCE TO RELATED APPLICATIONS

The present application is the national stage under 35 U.S.C. 371 ofinternational application PCT/IB00/00599, filed May 5, 2000 whichdesignated the United States, and which international application waspublished under PCT Article 21(2) in the English language.

TECHNICAL FIELD

Specifically, though not exclusively, the invention is usefully appliedfor packaging food products, pharmaceuticals, cosmetic and detergentproducts in the form of creams, pastes, liquids, powders, granules andhot-packed liquid products which solidify on cooling.

BACKGROUND ART

Reference is especially made to a container having two substantiallysimilar pouches facing one another, provided with a pair of externalwalls and a central wall joined at least along a part of its perimeterto the external walls, thus defining the pouches.

US patents U.S. Pat. No. 4,254,910 and U.S. Pat. No. 5,170,886 teachcontainers of the above-described type which are used for packingliquids, especially perfumes which are then transported as gas in an airmedium in order to disperse about a room. The containers comprise acentral wall which is permeable to gases and which is associated to thegas-impermeable external walls in such a way as to be removable.

In FR 2755673, which discloses a process as in the preamble of claim 1,a sachet type of container is formed from two sheets of plastic whichare welded together and between which a product is contained. A rigidmedian film forms a partition for dividing the container into twodistinct compartments. The partition extends beyond the perimeterdelimited by the compartments in order to provide a zone outside thecompartments to form a support. The sachet type container contains twocomponents which can be subsequently mixed to produce a product.

In U.S. Pat. No. 5,724,789 a multi-compartment dispensing package ismanufactured by feeding three sheetings of heat sealable flexible filmthrough a form-and-fill packaging instrumentation including an assemblydividing one sheet into two halves which become outer walls. Theperipherally sealed, juxtaposed, multi-compartment, flexible packageincludes a pair of outer walls and a separator wall disposed between theouter walls for dividing the package into a plurality of compartments.The package is adapted to be torn open to simultaneously dispense andadmix flowable material disposed within each of the compartments.

WO 98/26997 discloses a process for manufacturing a multicompartmentsachet wherein two webs are fed horizontally into a forming station intowhich are inserted several vacuum ports. One web forms the outer wallsof a sachet and the other web forms a dividing sheet.

The main aim of the present invention is to provide a process forforming containers with double pouches of the above-indicated type,which process is relatively rapid and economical.

An advantage of the invention is that it makes available a double pouchcontainer which is particularly suitable for dispensing two differentproducts at the same time—which products are kept separate until themoment they are dispensed.

A further advantage of the invention is to provide a double-pouchcontainer for two products, which can be placed in a room and whilethere dispense and disperse in the air, over a period of time, the twoproducts contained in it; the two products can also be dispensed in adetermined order.

A further advantage is that a double-pouch container for two single-doseproducts is provided, so that one of the products can be consumed whilethe other remains sealed and available for consumption at a later date.

A further advantage is that a double-pouch container is provided for oneproduct, which means that the product can be directly consumed whileheld in the hand. These aims and advantages and others besides are allattained by the present invention, as it is characterised in the claimsthat follow.

Further characteristics and advantages of the present invention willbetter emerge from the detailed description that follows of somepreferred but non-exclusive embodiments of the invention, illustratedpurely by way of non-limiting examples in the accompanying figures ofthe drawings, in which:

FIG. 1 is a block diagram of a plant for forming double-pouch containersin heat-formable and heat-weldable material, according to the invention;

FIG. 2 is a perspective view of the infeeding station for the centralribbon of the plant of FIG. 1;

FIG. 3 is a lateral view of the manifold of the injector group of theplant of FIG. 1;

FIG. 4 is a section according to line IV—IV of FIG. 3;

FIG. 5 is a schematic is a schematic view in section of a pre-heatingstation of the plant of FIG. 1;

FIG. 6 is a schematic frontal view of a half-mould of the station ofFIG. 5;

FIG. 7 is a schematic view in section of the forming station of FIG. 1;

FIG. 8 is a schematic frontal view of a half-mould of the formingstation of FIG. 7;

FIG. 9 is a schematic view in section of the welding station of theplant of FIG. 1;

FIG. 10 is a schematic frontal view of a half-mould of the weldingstation of FIG. 9;

FIG. 11 is a schematic perspective view of a part of the plant of FIG.1;

FIG. 12 is a perspective view of a plurality of containers formed by theplant:

FIG. 13 is a side view of a first container made according to theinvention;

FIG. 14 is section XIV—XIV of FIG. 13;

FIG. 14 a shows the open container;

FIG. 15 is a lateral view of a second container made according to theinvention;

FIG. 16 is section XVI—XVI of FIG. 15;

FIG. 16 a shows the open container;

FIG. 17 is a side view of a third container made according to theinvention;

FIG. 18 is section XVIII—XVIII of FIG. 17;

FIG. 19 shows a side view of a fourth container made according to theinvention;

FIG. 20 shows section XX—XX of FIG. 19;

FIG. 21 shows section XXI_(—)XXI of FIG. 19;

FIG. 22 shows section XXII—XXII of FIG. 19;

FIG. 23 is a side view of a fifth container made according to theinvention.

DISCLOSURE OF INVENTION

With reference to the above-mentioned figures of the drawings from 1 to12, 1 denotes in its entirety a plant for forming double-pouchcontainers in heat-formable and heat-weldable material.

The plant 1 comprises a feeding and folding station 2 which supplies afilm of plastic material which film is separated into two externalribbons 3, situated side-by-side and joined at the bottom; the plantfurther comprises an infeeding station 4 of a centrally-arranged ribbon5 i.e. arranged between the external ribbons 3; the plant furthercomprises a first and a second preheating station 6 and 7 for theexternal ribbons 3, a welding station 9 for the external ribbons 3 andthe central ribbon 5, and a cooling station 10 for the formed and weldedcontainers 11.

The external ribbons 3 in arrival from the feeding and folding station 2are kept in a substantially vertical and slightly separated position andadvance continuously in a horizontal line.

The infeeding station 4 superiorly comprises a transversal reel 12 forfeeding the central ribbon 5 and a plurality of horizontal rollers 13for keeping the central ribbon 5 stretched during the unwinding of thereel 12 and the vertical insertion from above of the central ribbon 5into the space between the two external ribbons 3, which as mentionedare kept slightly apart.

Advantageously the insertion of the central ribbon 5 between the twoexternal ribbons 3 is favoured by the inclusion of an inclined fixedspindle 14, which, located interiorly of the advancement line of theexternal ribbons 3, receives the central ribbon 5 from above anddeviates it in order to insert it continuously between the separatedexternal ribbons 3.

Two vertical rollers 15, arranged downstream of the spindle 14 andexternally of the external ribbons 3, receive the external ribbons 3with the central ribbon 5 already inserted between them and compacts theset of ribbons 3 and 5 with the help of a plurality of pliers 16distributed along the advancement line.

At the preheating stations 6 and 7, the forming station 8 and thewelding station 9, a forming fluid is introduced, for example hotpressurised air, which is inserted between the external ribbons 3through an injector group equipped with a manifold 17 which isinterpositioned between the half-moulds of the various stations workinglaterally.

The preheating stations 6 and 7 comprise a mould which has compartments18 that are sufficient to keep the external ribbons 3 separated while atthe same time they adhere to the walls of the compartments 18 by effectof the forming fluid inserted during the closing stage of the relativehalf-moulds 19.

The forming station 8 comprises a mould which is provided withcompartments 20 afforded in the relative half-moulds 21, which latterare shaped correspondingly to the final shape of the finished containers11.

The welding station 9 comprises a mould which is provided withcompartments 22 afforded in half-moulds 23, in which the already-formedcontainers are housed.

The manifold 17 has a longitudinal blind hole 24 for supplying thefluid, and communicates through a plurality of transversal pipes 25 withthe mouths 26 of the containers 11. The manifold 17 is preferably alsoprovided with a water cooling circuit 27 which prevents any containeroverheating at the various stations.

The pipes 25 have one end located at the mouths 26, which end is closedand in communication with the mouths through two lateral nozzles 28which enable uniform distribution of the forming fluid between theexternal ribbons 3.

At the position of the heating stations 6 and 7 and the forming station8, the manifold 17 inferiorly exhibits two separating blades 29,positioned vertical, distanced one from another and reciprocallyaligned, which blades 29 insert between the central ribbon 5 and theexternal ribbons 3.

The blades 29 enable the external ribbons 3 to be preheated and thus thecontainers 11 to be formed without the central ribbon 5 being undulyheated, so preventing any formation of blisters, air pockets and thelike due to excessive heat exposure.

The welding station 9 is provided with heat-welding equipment, ofwell-known type and not illustrated, which weld the central ribbon 5 andthe pair of external ribbons at the edges of the containers 11.

The forming fluid introduced in the various stations determines theexpansion of the external ribbons 3, made of plastic material, againstthe opposite hollow compartments afforded in the two half-moulds of therespective moulds.

The moulds are maintained at a temperature which softens the material,while being sufficiently low to prevent the external ribbons 3 fromwelding to the moulds themselves. For the same reason the gripping forceof the moulds must be sufficiently high to prevent the fluid fromescaping but not such as to weld the external ribbons 3 together.

The stations upstream of the forming station 8 operate at graduallyincreasing temperatures up until the softening temperature of theexternal ribbon 3 material is reached. The forming station 8 operates atlower temperatures than the upstream stations so as to stabilise theshape of the containers under formation. The cooling station 10downstream of the welding station 9 concludes the deformation of theexternal ribbons 3 and the subsequent stabilisation of the weldedsurface.

Advantageously, downstream of the cooling station 10 there will be acontainer filling station, a filled container-mouth permanent weldingstation and a cutting station for separating one or more adjacentcontainers in transversal planes which are perpendicular to the formingdirection.

The described plant actuates a process for forming double-pouchcontainers comprising the following stages: infeeding two continuousexternal ribbons 3, facing one another, in an advancement direction, toat least one insertion zone where a third, central ribbon 5 is insertedbetween the external ribbons 3; forming the pouches in the two externalribbons 3, after insertion of the central ribbon 5, by coupling the twoexternal ribbons 3 to two half-moulds having compartments the shape ofwhich corresponds to the shape of the finished pouches; welding thecentral ribbon 5 to the external ribbons 3 at the perimeter edges of theformed pouches.

The coupling of the external ribbons 3 to the two half-moulds isrealised, after insertion of the central ribbon 5, by injecting aforming fluid between the external ribbons 3 in order to determine theexpansion of the external ribbons 3 against the compartments of thehalf-moulds.

By using another plant (not illustrated), it would be possible to formthe pouches on the external ribbons 3 by coupling the external ribbons 3to two half-moulds before insertion of the central ribbon 5.

Preferably the two external ribbons are formed by folding a continuousfilm in order to produce a pair of side-by-side ribbons joined at theirbottoms.

Preferably the central ribbon 5, unwound from a transversal reel, isinserted continuously from above between the two external ribbons 3,held slightly apart and advancing in a substantially horizontaldirection.

In an embodiment of the process, at least two of the three ribbons aremade of a material of known type which disintegrates by effect of one ormore external agents.

The intermediate or central ribbon 5 can be considerably thinner thanthe two external ribbons without endangering the effectiveness of theseal and the integrity of the finished container.

The plant operates as follows.

The continuous external ribbons 3 of heat-formable and heat-weldablematerial are advanced from the feeding station 2, separated one from theother, to the infeeding station 4 of the central ribbon 5.

The central ribbon 5 is inserted between the external ribbons 3, thepack of ribbons is compacted and taken to the preheating stations 6 and7 where the central ribbon 5 is isolated by the blades 29 and theexternal ribbons 3 are heated and slightly expanded by the action of apressurised forming fluid in compartments of relative moulds.

On quitting the preheating stations 6 and 7, the external ribbons 3proceed to the forming station 8, where they are expanded against thecompartments of the mould in order to realise the walls of the container11. The central ribbon 5 is kept isolated from this part of the processby the blades 29.

On leaving the forming station 8, the external ribbons 3 and the centralribbon 5 are taken to the welding station 9, where the external ribbons3 and the central ribbon 5 are heat-welded along the perimeter edge ofthe containers 11.

When the containers 11 leave the welding station 9, by now formed andwelded, they are sent to the cooling station 10 and thereafter to thefilling station, the closing station and the mouth permanent-weldingstation, and finally to the cutting station.

The following, with reference to figures from 13 to 23, is a descriptionof various containers which can preferably be obtained using the plantand the process of the invention.

FIGS. 13 and 14 illustrate a container 40 having two closed pouches 41and 42 which are basically similar, face one another, are isolated onefrom the other, with each of them containing a product.

The container 40 comprises a pair of external walls 43 and 44 and aseparator central wall 45 coupled along its perimeter to the externalwalls 43 and 44, thus forming the pouches. The central wall 45separating the two pouches is made of a material which is impermeablewith regard to the two products contained in the pouches, and keeps theproducts apart up until the moment of use of at least one of them.

The products in the pouches might be two different ones, which are mixedtogether only when the container is opened. The products might be, forexample, two medical substances which interact on mixing; or they mightbe two single components in a bi-component product (for example atoothpaste) which is combined only at moment of use.

The container exhibits at least one breakable end 40 a, which relates toboth pouches and whose fracture determines the opening of the adjacentoutlet mouths 41 a and 42 a (FIG. 14 a), one for each pouch, separatedone from the other by the central wall 45 but through which the productscontained in the pouches can flow out.

The external walls 43 and 44 can be made of a flexible material, and theoutflow of the two products (preferably liquid or paste) can beachieved, after breaking the end 40 a, by squeezing the external walls43 and 44.

The breakable end 40 a can be manually broken by the user. In thepresent case the end 40 a comprises two parts of pouch, each having anarrower section with respect to the rest of the pouch. These narrowerparts are side-by-side and separated by the central wall 45.

The breakable end 40 a has two fracture lines 46 and 47 predisposed tofacilitate the breakage of the end 40 a. Each fracture line comprises arecess cut into the peripheral part of the container, in a zone wherethe three walls which define the pouches are coupled one to another. Therecesses preferably go all the way through the plastic, as in theillustrated embodiment (which means that they cut both the externalwalls and the central wall) but can also be only partially penetrating.The recesses are situated at the opposite sides of the breakable end 40a and extend almost up to the end 40 a itself.

The recesses are made at a cutting station predisposed downstream of thefinal welding station of the filled containers.

The double-pouch container is especially suitable for simultaneousdispensing of two different products kept separate until the moment ofdispensing.

In an embodiment which is not illustrated, the breakable end 40 a canexhibit two recesses, each made in a respective external wall 43 and 44,to enable separate opening of the two pouches, first one and then theother. The operation is facilitated if the central wall 45 is made in aflexible material.

In another embodiment, the opening of the two pouches can be realised,rather than by breaking a part of the container, by using a closuredevice (for example a cap, a top, a tongue) applied to the containerafter it has been filled.

The three walls 43, 44 and 45 are preferably made of a heat-formable andheat-weldable material, for example plastic.

FIGS. 15 and 16 illustrate a container 50 having two external walls 51and 52 which externally delimit the pouches and which are coupled to acentral wall 53 in such a way that they can be peeled away.

The central wall 53 exhibits one end 53 a which is not coupled to theexternal walls, but which terminates internally of the pouches, thusleaving an opening 54 which sets the pouches in communication with eachother. At the opposite end 53 b the central wall 53 functions as ahandle (once the external walls have been peeled away) so that theproduct can easily be eaten (FIG. 16 a); thus the central wall 53functions as a support for the product.

Peeling away the external walls is made easier by the presence of twotongues which are none other than two ends of the external walls notwelded to the central wall 53.

FIGS. 17 and 18 illustrate a third type of container 60 in which theexternal walls 61 and 62 are coupled to the central wall 63 so that theycan be peeled away.

The central wall 63 is made of a material which protects the productscontained in the pouches from the outside environment, especially if theproducts are in the food category. The material of the central wall 63is also impermeable to any odours in the atmosphere, or smells issued bythe products themselves, so that the food qualities of the products arewell-protected.

The container 60 is opened by peeling away the external walls from thecentral wall 63. Two tongues 64 and 65, none other than two ends of theexternal walls not welded to the central wall, facilitate containeropening.

The container is made such that first one external wall, then the other,can be peeled away. The container is therefore convenient for containingtwo single doses of a same product, so that one can be consumed and theother saved for later consumption.

In the above-described double-pouch containers, it can be arranged thattwo of the three walls defining the pouches are made of a material, ofknown type, which disintegrates by effect of one or more determinantexternal agents (for example, chemicals, mechanical agents, atmosphericagents, heat factors, etc.) So that the product in at least one of thepouches is released to the outside environment. In particular, all threewalls can be made of a material liable to disintegrate. The materialcould be, for example, water-soluble.

At least one of the three walls can be made of a disintegrating materialhaving different characteristics from the disintegrating material ofwhich at least one other of the three walls is made. This differentcharacteristic is preferably connected to the time needed todisintegrate, so that one of the products can be released to the outsidebefore the other. The container might exhibit, for example, an externalwall destined to disintegrate first, leaving the product in one of thepouches free to disperse into the atmosphere, while the other two wallswill disintegrate later, freeing the other product after the first hascarried out its activity.

Figures from 19 to 22 illustrate a container 70 having two basicallysimilar closed pouches 71 and 72 which are face-to-face but isolatedfrom each other, each of which contains a product.

The container 70 comprises a pair of external walls 73 and 74 and aseparator central wall 75 coupled along its perimeter to the externalwalls, thus forming the pouches. The central wall separating the twopouches is made of an impermeable material which keeps the two productsseparate.

The products contained in the two pouches can be ones which are intendedto combine, even if they are different to each other, perhaps at adistance of time, i.e. without mixing (for example, a single dose ofshampoo followed by a dose of hair conditioner, which will be usedimmediately after the shampoo).

The container 70 exhibits at least two easy-break ends 76 and 77,separate and distanced one from the other, in which a first end 76relates to one of the pouches 72 while a second end 77 relates to theother of the pouches 72. An easy-break end, associated to a pouch,comprises a relatively-narrow appendix of the pouch. The appendix isdelimited by the separator central wall 75 and by one of the twoexternal walls 73 or 74, while the other external wall, 74 or 73, in thezone situated at the other end from the appendix, is coupled to thecentral wall 75. Each appendix is cut in two by a respective fractureline 78. There are at least two fracture lines 78, one for eachappendix. The fracture lines 78 do not intersect and are relativelydistant from each other. The breakage of one of the two fracture lines78 opens one of the two pouches, leaving the other pouch intact.

The user can open one pouch, for example pouch 71, by breaking only oneof the ends, i.e. the second end 77, without running any risk ofbreaking the other end 76. The second end 77 is in a zone of thecontainer where the central wall 75 and the external wall 74, whichtogether define the pouch 72, are welded one to the other. Thus bybreaking the second end 77 the pouch 72 remains sealed. A similarsituation exists for the first end 76, which is situated in a zone ofthe container in which the central wall 75 and the external wall 73,which together define the pouch 71, are welded to each other.

FIG. 23 illustrates a container 80 which differs from container 70 inthat the latter has a flat bottom 81 and can be set down independentlyon a surface. The two easy-break ends are at an opposite end from thebottom 81. During manufacture of this container the forming fluid isblown through an opening situated between the two easy-break ends, againat the opposite end from the bottom 81. 82 denotes the zone of thecontainer 80 where during the forming operation the hole for introducingthe forming fluid was situated. In container 70 of FIG. 19, the fluidintroduction hole, denoted by 79, is located on an opposite side to theside where the easy-break ends 76 and 77 are situated.

Another type of container, not illustrated, which can be formed by thedescribed plant, is made of heat-formable and heat-weldable material forproducts designed to emanate and disperse in a surrounding environment,such as perfumes and the like. The container comprises two pouches,separated by a central permeable wall. The pouches and the central wallare welded together along the perimetral edge.

The central wall can compirse an internal layer and two external filmswhich are destined to be welded to the external walls of the pouches.The central wall is made of materials which render the adhesion forcebetween the external films and the internal layer lower than theadhesion force between the external films and the external pouch wallsafter they have been welded together.

The two external films can be made of a gas-permeable plastic material.The internal layer uniting the two films can be a peelable resin. Theadhesion force guaranteed by the peelable resin is lower than thewelding force between the films and the external walls of the pouches,which results in the films being easily peelable.

The partial or total opening of the containers is done at the internallayer of the permeable central wall, making possible the emanation ofthe contents of the two pouches into the surrounding atmosphere.

This type of container is especially suitable for scenting closedenvironments, such as wardrobes, drawers, linen cupboards and so on. Thecontainer can be used both in vertical and horizontal configurations, donot require removal of a supplementary film, and have no permeable partin direct contact with shelves or other surfaces, as this part isinternal of the pouches containing the product. Also, in comparison toother traditional products of the type and size, the present containersexhibit an emanation surface which is twice as big, as the scents exitat the same time from the two permeable films of the central wall weldedto the respective pouches.

All of the above-described containers can be made with the separatorcentral wall thinner than the plastic sheets from which the externalwalls are made. Thanks to this very thin central wall, a saving can bemade in terms of material without weakening the sealing function of thecontainer.

All of the above-described containers can be manufactured using theplant described in figures from 1 to 12, and all can be made using anyone of the above-described processes.

1. A process comprising the following steps: advancing two continuousexternal webs, facing one another, in an advancement direction, to atleast one insertion zone where a third, continuous central web isinserted between said external webs; forming pouches from said externalwebs and said central web, after inserting of said central web, byintroducing, at a forming station, said external webs and said centralweb between half-mould compartments, having a shape corresponding to afinal shape of said pouches, and injecting a forming fluid between saidexternal webs and said central web through an opening so as to expandsaid external webs against said compartments; welding said central webto said external webs along a peripheral zone of said pouches and alongan outline of each pouch so as that said opening remains; filling eachpouch with a product through said opening at a filling station; andsealing each pouch by closing said opening.
 2. A process according toclaim 1, and further comprising interposing a pair of vertical separatorblades between said central web and said external webs during saidforming, said vertical separator blades being parallel to one anotherbut spaced apart one from another.
 3. A process according to claim 2,and further comprising preheating said external webs before saidforming, during said preheating said pair of vertical separator bladesbeing interposed between said central web and said external webs so asto prevent said central web from being preheated.
 4. A process accordingto claim 1, and further comprising unwinding said central web from atransversal reel so as to insert continuously from above said centralweb between said external webs during said advancing in a horizontaldirection.
 5. A process according to claim 4, wherein said central webis unwound vertically from said reel and is deviated so as to beinserted continuously between said external webs.
 6. A process accordingto claim 1, wherein after said inserting, said external webs and saidcentral web are compacted together.
 7. A process according to claim 1,wherein said external webs are obtained by folding of a continuous film,so as to define a pair of webs situated side-by-side and reciprocallyconnected at the bottom thereof.
 8. A process according to claim 1,wherein at least two of said webs are made of a material whichdisintegrates by effect of one or more external agents.
 9. An apparatuscomprising: a feeding station intended for feeding two continuousexternal webs, facing one another, in an advancement direction; aninserting station intended for inserting a central web between saidexternal webs; a forming station provided with half-mould compartmentsand arranged for forming pouches from said external webs and saidcentral web by shaping said external webs according to a shape of saidcompartments, the forming station being further provided with aninjector group which serves to inject a forming fluid between saidexternal webs and said central web so as to expand said external websagainst said compartments; a welding station so configured as to weldsaid central web to said external webs along a peripheral zone of saidpouches and along an outline of each pouch so as to define an openingthrough which said forming fluid is injected; a filling station arrangedfor filling each pouch with a product through said opening; and asealing station intended for sealing each pouch.
 10. An apparatusaccording to claim 9, and further comprising a preheating station forpreheating said external webs, said injector group comprising a manifoldextending through said preheating station, said forming station and saidwelding station.
 11. An apparatus according to claim 10, wherein at saidpreheating station and at said forming station said manifold is providedat the bottom with a pair of vertical separating blades, parallel toeach other and set at a distance one from another, said verticalseparating blades being intended to be positioned between said centralweb and said external webs to prevent heating of said central web. 12.An apparatus according to claim 10, wherein said manifold comprises alongitudinal blind-hole for feeding said forming fluid between saidexternal webs and said central web through a plurality of transversalpipes.
 13. An apparatus according to claim 12, wherein said transversalpipes comprise at least two lateral nozzles arranged at opposite sidesof said central web.
 14. An apparatus according to claim 10, whereinsaid manifold is provided with a cooling circuit in which water maycirculate to prevent overheating of said webs.
 15. An apparatusaccording to claim 9, wherein said inserting station is provided at thetop with a transversal reel for continuously feeding said central webfrom above between said external webs while the latter are advancingmutually separated in a horizontal direction.
 16. An apparatus accordingto claim 15, wherein said inserting station comprises a fixed inclinedspindle arranged for receiving said central web vertically unwound fromsaid reel and for deviating said central web so as to insert itcontinuously between said external webs.
 17. An apparatus according toclaim 9, and further comprising a compacting arrangement for compactingtogether said external webs and said central web, downstream of saidinserting station.
 18. An apparatus according to claim 17, wherein saidcompacting arrangement is constituted by pairs of rollers and pliersdistributed along a path of said external webs and of said central webin said advance direction.